Abstract: The history of digital signal processing and the digital signal processor (DSP) is reviewed. As is well known, real-time implementation is crucial in the applications of digital signal processing in which the DSP plays an important role. Certain key techniques, such as the types and type selection of DSPs, their development equipment, real-time software development and so on are then described. Finally, some practical applications such as speech coding hardware, video telephone and video conference systems, DSP parallel processing systems for sonar and radar are also described